An interesting and difficult move. Ding removes the pawn from the seventh rank so that a rook on c7 doesn't attack it.
42. h4h6 White is a healthy pawn up. The knight, however, is the trickiest piece in chess. 42... d5c3  43. h6c6  43... c3e4  44. f1e1 A human reaction, preventing the check on d2. Unfortunately, human moves aren't always the best.